Barrel biasing means for automatic firearm



March 22, 1966 D; l. DWYER, sR 3,241,449

BARREL BIASING MEANS FOR AUTOMATIC FIREARM Filed July 23, 1964 2Sheets-Sheet 1 FIG.4

nun-11ml g2; FIG.5

March 22, 1966 n. DWYER, SR

BARREL BIASING MEANS FOR AUTOMATIC FIREARM 2. Sheets-Sheet 2 Filed July23, 1964 BY ZZ/M United States Patent 3,241,449 BARREL BIASING MEANS FORAUTOMATIC FIREARM Daniel I. Dwyer, Sr., 4167 Palmetto Way, San Diego,Calif. Filed July 23, 1964, Ser. No. 384,956 Claims. (Cl. 89-196) Thepresent invention relates to a barrel biasing means for an automaticfirearm, and more particularly to a biasing means operative to maintainthe barrel of such a firearm in its firing axis until the bullet hasleft the barrel.

Automatic firearms necessarily are characterized by a number ofloose-fitting parts in order to facilitate mass production and providereliable automatic operation. This is particularly true in the case ofmilitary-weapons such as the standard .45 caliber automatic pistol, suchas is described in War Department Technical Manual TM9- 1295 under thedesignation M1911. This weapon is recoil-operated, magazine-fed, andself-loading. The gas generated from a cartridge fired in the pistol isutilized to extract and eject the empty cartridge case, cock the hammer,and force the slide to its rearrnost position, thereby compressing arecoil spring. The action of the recoil spring forces the slide forwardto feed a live cartridge from the magazine into the chamber for anotherfiring operation. It is in connection with maintenance of the barrel inits firing axis upon initial recoil of the barrel and slide that thepresent invention is concerned.

More particularly, the slide and barrel in the standard .45 caliberM1911 pistol are interlocked in their forward firing positions bycooperating ribs and grooves provided thereon, and the barrel is mountedto the slide for tilting at the rearward portion of the slide to unlockthe barrel from the slide. When the slide is driven rearwardly upondetonation of a cartridge charge, the barrel is carried rearwardly withit by reason of the interlocking ribs and grooves. However, the barrelmoves only a short di tancc, approximately one-eighth of an inch, atwhich point the rearward extremity of the barrel is pivoted or tilteddownwardly relative to the slide to unlock the slide and permit it tocontinue rearwardly to pick up a fresh cartridge from the magazine.

In the M1911 military pistol the rearward extremity of the barrel ispivotally connected to the frame by a barrel link to effect the downwardtilting of the barrel relative to the slide. The barrel link rotatesabout pins carried by the barrel and frame, and reliability of operationrequires that generous clearances be provided at these pins. On theother hand, these clearances are undesirable in that during actualfiring the barrel can deviate from its true firing axis by the amount ofsuch clearances. Since these deliberate clearances, as well asmanufacturing tolerances and deflections of the pistol components underload, are cumulative, the rearward extremity of the barrel is often outof alignment with its true firing axis two or three thousandths of aninch or more when it is in its firing position. Moreover, immediatelyupon initiation of the barrel recoil movement with the slide, therearward extremity of the barrel tends to be prematurely pusheddownwardly even farther out of its firing axis by the recoil forces.That is, the barrel is undesirably driven out of its firing axis priorto the time the barrel link positively tilts it, and hence prior to thetime the "bullet has left the barrel.

Accordingly, it is an object of the present invention to provide abiasing means to urge the rearward portion of the barrel upwardlyagainst the slide, including the period of initial recoil of the barreland slide, whereby the barrel is maintained in its true firing axisuntil it is positively tilted out of its interlocked relation with theslide. In

this regard, although the present invention is particularly "ice adaptedfor use in connection with the standard military .45 caliber pistol inwhich the slide and barrel are connected by a barrel link, it is to beunderstood that the biasing means of the present invention has broaderutility in substantially eliminating or taking up ordinary manufacturingtolerances and undesirable clearances resulting from wear and the likeoccurring in pistols in which the rearward portion of the barrel isguided by means other than a barrel link, such as by slots or cammingopenings provided on the barrel and cooperative with pins mounted to theframe.

Another object of the invention is to provide a biasing means of theaforementioned character which may be quickly and easily incorporated ina standard military type .45 caliber pisiol by merely replacing theconventional barrel link and recoil spring guide thereof with a barrellink and spring guide modified in accordance with the invention.

A further object of the invention is the provision of a biasing means ofthe aforementioned character which, in another embodiment, is adaptedfor incorporation in the standard .45 caliber military type pistol byreplacing only the recoil spring guide with a modified guide, or, in yetanother embodiment, by replacing only the usual slide stop pin with amodified stop pin.

Another object of the invention is the provision of a biasing means ofthe aforementioned character which is relatively inexpensive tomanufacture, easily installed in existing firearms, extremely reliablein operation, and adapted to significantly improve the accuracy of thefirearms with which it is associated.

Other objects and features of the invention will become apparent fromconsideration of the following description taken in connection with theaccompanying drawings, in which:

FIG. 1 is a side elevational view of a standard .45 caliber militarypistol embodying a biasing means according to the present invention, theforward portion of the pistol being sectioned for clarity;

FIG. 2 is an enlarged detail view of the barrel link, recoil springguide, and surrounding portions of the pistol which is illustrated inFIG. 1;

FIG. 3 is an enlarged detail view of a modified barrel link according tothe present invention;

FIG. 4 is a view taken along the line 44 of FIG. 3;

FIG. 5 is an enlarged longitudinal cross-sectional view of a modifiedrecoil spring guide according to the present invention;

FIG. 6 is an enlarged end elevational view of the recoil spring guide ofFIG. 5;

FIG. 7 is a side elevational view of the leaf spring forming a part ofthe recoil spring guide of FIG. 5, the leaf spring being illustrated inits relaxed state;

FIG. 8 is a plan view of the leaf spring of FIG. 7;

FIGS. 9 through 11 are enlarged detail views of the barrel link andrecoil spring guide of FIG. 1, illustrating progressive changes in thepositions of these components during travel from their firing positionsto their recoil positions;

FIG. 12 is an enlarged side elevational view, partially in section,showing a differently modified barrel link and biasing means, whichconstitutes a second embodiment according to the present invention;

FIG. 13 is a partial View of another form of modified recoil springguide, which constitutes a third embodiment of the present invention;

FIG. 14 is an end elevational view of the rearward ex tremity of therecoil spring guide of FIG. 13;

FIG. 15 is an end elevational view of the recoil spring guide of FIG.14;

FIG. 16 is a transverse cross-section of a modified form r, of slidestop pin constituting a fourth embodiment of the present invention; and

FIG. 17 is a view taken along the line 17-17 of FIG. 16.

Referring now to the drawings, and particularly to FIGS. 1 and 2thereof, there is illustrated a standard .45 caliber military pistol ofthe M1911 type, and incorporating the biasing means of the presentinvention. In order to better understand the operation of the presentbiasing means, a brief explanation will first be made of the componentsand operation of the pistol 20'.

The pistol 20 comprises a receiver or frame 22 which includeslongitudinally oriented ribs and grooves (not shown) which slidablycooperate with complemental ribs and grooves (not shown) of an elongatedbreech slide 24, and also comprises an elongated reaction or recoilspring 26 which biases the slide 24 toward its forward position, asillustrated in FIG. 1. The slide 24 mounts an elongated barrel 28 fortilting movement relative to the slide, and includes a rearward breechblock portion 30 having a vertical front face (not shown) which isengaged with the rearward end of the barrel 28 when the slide 24 is inbattery, that is, in its forward firing position.

The rearward portion of the recoil spring 26 is located within anupwardly open, longitudinally oriented spring recess 34 provided in theforward portion of the frame 22, as best illustrated in FIG. 2, and arecoil spring guide 36 is positioned within the recess 34 for mountingthe rearward extremity of the spring 26. The guide 36 includes at itsrearward extremity a peripheral flange 38 which abuts against a shoulder40 defining the rearward end of the spring recess 34. Such abutmentlimits rearward movement of the spring guide 36 under the impetus of thespring 26 and serves as a reaction surface for the compressive force ofthe spring 26 against the frame 22. The upper portion of the peripheralspring guide flange 38 includes an arcuate saddle 42, as bestillustrated in FIG. 6, which underlies and engages the undersurface ofthe adjacent barrel 28 to prevent upward movement of the spring guide 36relative to the frame 22. In addition, the rearward extremity of thespring guide 36 includes a cylindrical portion which projects rearwardlyof the peripheral flange 38 and seats at its lower periphery against anarcuate, complementally contoured wall which defines a recess 44 in theframe rearwardly of the shoulder 40 and terminating in a rearward wall(not shown).

The forward extremity of the barrel 28 is mounted to the forwardextremity of the slide 24 for relative longitudinal slidable movementand for limited transverse movement to permit slight tilting of therearward portion of the barrel relative to the slide. More particularly,an elongated recoil spring plug 46 receives the forward extremity of therecoil spring 26 within its hollow interior and transfers the bias ofthe spring 26 to the slide 24 by means of a cylindrical barrel bushing48 suitably removably secured to the forward end of the slide 24 inencompassing relation relative to the forward end of the barrel 28. Withthis arrangement, the recoil spring 26 acts at all times to bias theslide 24 forwardly to its firing position.

Forward movement of the slide is limited by engagement of the barrelwith a slide stop pin 50 which is pivotally disposed through alignedtransverse openings in the frame, generous clearances being afforded topermit the stop pin 50 to be freely inserted and removed. The stop pin50 extends through the recess 44 adjacent the rearward extremity of therecoil spring guide 36, and cooperates with barrel means which dependfrom the rearward extremity of the barrel 28 for guiding the movement ofthe barrel 28 as desired. In the standard .45 caliber pistol this barrelmeans is constituted by a pair of transversely spaced-apart barrel lugs52 forming an integral part of the rearward portion of the barrel; atansverse barrel link pin 54 press-fitted through suitable alignedopenings provided in the lugs 52; and a barrel link 56, which isgenerally oval and includes openings at its upper and lower portions forpivotally receiving, respectively, the barrel link pin 54 and the slidestop pin 50.

The components described above are all standard with the military M1911.45 caliber pistol except for the recoil spring guide 36 and the barrellink 56, which have been modified in certain respects which willhereinafter be described in detail.

In operation, the breech slide 24 and the barrel 28 are interlocked intheir forward firing positions, as shown in FIG. 1, by transverse ribsand grooves formed, respectively, on the upper rear portion of thebarrel and in the undersurface of the top wall of the hollow interior ofthe slide 24, as indicated at 58. In such firing positions of the slideand barrel, the slide is biased forwardly by the recoil spring 26, andthe barrel 28 is constrained against forward movement by engagement withthe slide stop pin 50 of the forward faces of a pair of dependingcamming surfaces 60 which are integral with the barrel lugs 52. Theslide stop pin 56 thus constitutes the means by which the slide isconstrained against forward movement beyond its normal firing position,it being particularly noted that the bias of the recoil spring 26 actingagainst the slide 24 always develops a pressure of the camming surfaces60 against the slide stop pin 59 when the barrel and slide are in theirfiring positions.

Upon detonation of the cartridge charge, the breech slide 24 and thebarrel 23 recoil together for approximately one-eighth of an inch,during which time the bullet theoretically leaves the barrel beforethe'rearward portion of the barrel tilts or swings downwardly on thebarrel link about the axis of the slide stop pin 50. However, aspreviously indicated, the cumulative tolerances and clearances betweenthe barrel link and the slide stop and barrel link pins, andparticularly the tolerances necessary to permit pivotal movement of thebarrel link 56, are such that the rearward portion of the barrel isoften prematurely tilted out of its firing axis under the action of therecoil forces. These tolerances are only in the order of a fewthousandths of an inch, but suificient to seriously affect the accuracyof the pistol 20.

At approximately the time of passage of the bullet out of the barrel 28,the rear portion of the barrel is pivoted downwardly away from the slideby the barrel link, unlocking the breech slide 24 from the barrel.Further rearward travel of the barrel is stopped by engagement betweenthe rearward edges of the barrel lugs 52 and the rearward wall of therecess 44. However, the momentum of the breech slide 24 carries itrearwardly for extracting and ejecting the shell and cocking the firingmechanism, all as will be apparent to those skilled in the art.

During the rearward movement of the slide 24, the recoil spring 26 iscompressed and tends to return the recoiling barrel and slide to theirforward firing positions as soon as the rearward movement of the slideis arrested.

Upon forward movement of the slide, the barrel 28 remains in itsrearward or recoil position until the vertical front face of the breechblock portion 30 engages the rearward end of the barrel 28, whichupwardly swings or tilts the rearward end of the barrel about the axisof the barrel link pin 54. The barrel is thereby moved into interlockingengagement with the slide, and the barrel and slide then move forwardlytogether until the camming surfaces 60 of the barrel lugs 52 engage theslide stop pin 50 and stop the barrel, thereby stopping the slide aswell.

The foregoing discussion of the military M1911 .45 caliber pistol isexemplary of an automatic firearm in bore.

which necessary operating clearances undesirably permit the barrel tomove out of its true firing axis, particularly during initial recoilwhen relatively high recoil forces are imposed upon those componentslinking the barrel to the frame.

In accordance with the present invention, bias means are provided foroperating upon the barrel means which depend from the rearward portionof the barrel and which cooperate with means on the frame for guidingthe travel of the barrel. Such barrel means in the military M1911 .45caliber pistol are constituted by the barrel lugs 52 and the barrel link56, and it is upon one or the other or both of these that the presentbias means acts to urge the rearward portion of the barrel upwardly andagainst the slide.

The bias means of FIGS. 111 is installed in the pistol by removing theusual recoil spring guide carried by the frame in the spring recess 34and replacing it with the guide 36, which is identical to the standardrecoil spring guide in every respect except as follows. The guide 36 ischaracterized by an elongated leaf spring 62 which is secured within thehollow interior or bore of the guide 36 and projects rearwardlytherefrom into the frame recess 44. The guide 36 also includes arearwardly projecting lower portion 64 which extends into the framerecess 44 in substantially coextensive relation with the rearwardlyprojecting portion of the leaf spring 62. In addition, the modifiedspring guide 36 includes a transverse pin 66 disposed through the guide36 immediately rearwardly of the peripheral flange 38 for engagementwith the upper surface of the leaf spring 62 to thereby limit upwardmovement or travel thereof.

The spring 62 is preferably made of a spring steel characterized byresilience and high strength, and includes a bend or bowed portion 68having an amplitude greater than the internal diameter of the springguide 36 whereby, when the leaf spring 62 is forcibly driven into theinterior of the spring guide 36, the spring is deformed from the relaxedstate illustrated in FIG. 7 to the stressed state illustrated in FIG. 5.In this stressed condition the spring tends to rigidly grip the interiorwalls of the spring guide In addition, the width of the spring is alsomade such that it bites into the metal of the guide during installationto prevent the spring from moving longitudinally or rotationallyrelative to the guide. The rearward portion of the spring is preferablyrearwardly tapered in width, as at 70 in FIG. 8, to provide freedeflection of the projecting portion of the spring in an arc having amore nearly common radius throughout the arc. That is, the arc ofmovement of the projecting spring portion upon deflection is therebycharacterized by common radii having their center in substantialvertical alignment with the lower portion 64 of the spring guide 36.With this arrangement, when the spring is deflected downwardly theprojecting guide lower portion 64 tends to afford a firmer seat for thespring guide upon the lower wall of the frame recess 44 and preventlongitudinal tilting of the spring guide. A satisfactory spring 62 hasbeen made of inch thick spring sheet stock which is inch wide and tapersrearwardly to inch. However, it will be apparent that the material,thickness, width, and configuration may be varied as desired so long asthe spring is capable of providing the described biasing action.

One other component of the standard military pistol is also replaced.The usual barrel link is removed, and the link 56 is installed instead.The link 56 is similar to the usual barrel link in all respects exceptthat the link 56 is characterized by a forwardly projecting camming kneeor surface 72, as best illustrated in FIGS. 3 and 9 through 11.

In FIG. 9 the positions of the leaf spring 62 and barrel link 56 areillustrated in their firing positions, in which the axis of the barrellink pin 54 is slightly forward of the axis of the slide stop pin 50. Inthis position of the barrel link 56, it is to be particularly noted thatthe camming surfaces 72 is urged downwardly against the spring 62 byreason of the biasing of the slide and barrel forwardly by the recoilspring 26. The bias developed by reason of the downward deflection ofthe leaf spring 72 urges the barrel link 56 upwardly, taking up theclearances or play between the openings in the link 56 and the pins 54and 50, and particularly at the slide stop pin 50. As will be apparent,the upward urging of the spring 62 against the barrel link 56 operatesto urge the rearward portion of the barrel 28 into close engagement withthe upper interior wall of the slide 24. A satisfactory leaf spring 62has been tested which is characterized by a bias force on fulldeflection of approximately 15 pounds, which is more than ample to takeup the few thousandths of an inch in clearances which usually arepresent.

FIG. 10 illustrates the position of the spring 62 and barrel link 56immediately subsequent firing of a cartridge and during initial recoilof the barrel and slide. It is to be noted that the leaf spring 62remains deflected downwardly to a considerable extent for imposing acontinuing bias upon the barrel 28 to urge it upwardly against the slideand maintain it in a straight line path until positive tilting thereofby the barrel link 56.

FIG. 11 illustrates the spring 62 and link in their recoil positions,wherein the camming surface or knee 72 is out of engagement with thespring 62. As will be apparent, when the slide subsequently movesforwardly into engagement with the barrel, the barrel is pivoted aboutthe axis of the slide stop pin 50, and the camming knee 72 again engagesand deflects the leaf spring 62. Thus, the interengagement between thebarrel link 56 and the leaf spring 62 provides what might be termed astraight line motion of the barrel 28 during initial recoil, prior topositive downward tilting of the rearward portion of the barrel by thebarrel link 56. Accordingly, the barrel is maintained in its true firingaxis until the bullet has left the barrel.

Referring now to FIGS. 13 through 15, there is illustrated another meansfor spring-loading the barrel so as to obtain the desired straight linemotion during initial recoil. The standard M19llA pistol components areused, including the barrel 28 with its usual depending lugs 52 mountingthe barrel link pin 54, and including a standard barrel link 74pivotally mounted to the barrel link pin 54 and pivotally mounted to theusual slide stop pin 50. However, a modified form of recoil spring guide76 is utilized which includes a rearwardly projecting lower cammingportion 78 which tapers rearwardly and downwardly from the usualperipheral flange 38 to form a camming surface which is upwardlyinclined in a forward direction. The base of the camming portion 78includes a longitudinal slot 80 for freely accommodating the pivotalmovement of the barrel link 74 therewithin.

In operation, the barrel 28 in its firing position is urged forwardly bythe slide, which is itself biased forwardly by the recoil spring 26.This brings the camming surfaces 60 of the barrel lugs 52 intoengagement with the spring stop pin 50 and limit forward travel of theslide beyond its normal firing position, as previously described.However, the camming portion 78 projects rearwardly sufiiciently toengage and exert an upward bias against the underside of the slide stoppin 50 because of the rearward bias of the recoil spring 26. That is,upon engagement of the camming portion 78 within the stop pin 50,

r the forwardly and upwardly tapering surface of the camming portion 78tends to urge the stop pin 50 upwardly under the bias of the recoilspring 26.

Inasmuch as the stop pin 50 is mounted in openings in the frame whichhave generous clearances relative to the stop pin, as previouslydescribed, the stop pin 50 is movable upwardly relative to the frame 22by the previously described bias force for forcibly engaging the barrellink and biasing it upwardly. This takes up existing clearances andurges the barrel upwardly against the slide affording the improvedpistol accuracy previously adverted to.

Referring now to FIG. 12, there is illustrated still another embodimentof the present invention wherein the conventional components of thestandard military pistol are utilized except for replacement of theusual barrel link with a modified barrel link 82 which is characterizedby a bottom camrning surface or cam lobe 84. In addition, a bias meansconstituted by a compression spring 86 is mounted within a vertical bore88 provided in the frame 22 and opening into the frame recess 44. Thelower end of the bore 88 is threaded to receive a threadedspring-retaining plug 90, which is also rotatable to adjust the bias ofthe spring. The upper end of the bore 88 is characterized by adiminished diameter portion or ball seat 92 which retains a ball 94within the bore 88, while permitting a portion of the ball to projectabove the frame 22 for engagement with the cam lobe 84 when the barreland slide are in their firing positions.

The spring 86 urges the ball 94 upwardly against the cam lobe 84 tothereby bias the barrel link 82 upwardly and remove or compensate forundesirable clearances, as previously described. The bias against thebarrel link tends to urge the barrel against the slide and therebymaintain the barrel in its firing axis during the firing and initialrecoil phases of the pistol operation.

Referring now to FIGS. 16 and 17, yet another embodiment of the presentbiasing means is illustrated. Again, the standard components of themilitary .45 caliber pistol are utilized for the most part. However, amodified slide stop pin 96 is utilized, being disposed through the usualtransversely aligned openings provided in the frame for the conventionalslide stop pin. The pin 96 is radially compressible or resilient at itsmidportion, which is achieved in the present embodiment by providing alongitudinal slot or split 98 in the pin 96, and outwardly bowing thesplit portions of the pin so that disposition of the pin 96 through thelower opening in the barrel link 74 can only be had by resilientlycompressing the central portion of the pin.

The slide stop pin 96 is radially compressible to allow the barrel link74 to pivot about the axis of the pin 96 upon rearward movement of thebarrel, and also to exert an upward bias upon the barrel link 74 in thefiring position of the barrel. That is, the outwardly bowedconfiguration of the central portion of the slide stop pin 96necessarily reduces the normal distance between the axes of the pin 96and the usual barrel link pin 54 so that when the barrel is pivoted intobattery or firing position, the barrel link 74 squeezes or axiallycompresses the stop pin 96. This in turn imposes an upward bias upon thebarrel link 74, and consequently upon the barrel, to thereby tend tomaintain the barrel in its firing axis both when the barrel is in itsfiring position and when it is undergoing initial recoil.

There are certain types of automatic pistols in which no barrel link isemployed, such pistols employing what is often referred to as aninclined plane arrangement, in which a cammed slot is provided on adepending portion of the rearward extremity of the barrel forcooperation with a usual slide stop pin carried by the frame. The splitstop pin 96 is equally adapted for use with this style of automaticpistol, although the mode of operation is slightly different from thatabove-described in connection with FIGS. 16 and 17. More particularly,use of the split stop pin 96 effects engagement thereof with the marginsof the cammed slot, depending barrel lugs, or analogous dependingportion of the rearward extremity of the barrel. Such engagement biasessuch portion upwardly and thereby biases the barrel upwardly into snugfitting relation with the slide. This has the effect of compensating fortolerances, clearances, and the like, as above-discussed, and eventhough no barrel link is employed.

From the foregoing it will be apparent that there has been provided abarrel biasing means adapted to eliminate or compensate for the usualmanufacturing and operational tolerances in those components ofautomatic firearms which cooperate to guide the travel of the barrelduring its operation. This is accomplished in the several embodiments byupwardly biasing the usual barrel means which depend from the rearwardportion of the barrel for cooperation with the frame to guide the barrelin its movernents. This in .turn upwardly biases the rearward extremityof the barrel against the slide. As previously indicated, the biasingmeans has broader utility, however, in that it is adapted to operateupon a variety of depending barrel means, whether or not such barrelmeans are constituted by a pivoting barrel link, or by an inclined planeform of barrel guidance means.

Various modifications and changes may be made with regard to theforegoing detailed description without departing from the spirit of theinvention or the scope of the following claims.

I-claim:

1. In an automatic pistol having a frame, a recoiling breech slide and arecoiling barrel mounted thereon for tilting at its rearward portionrelative .to said slide and including a depending portion mounting atransverse barrel link pin, means for interlocking said barrel and saidslide, a transverse slide stop pin mounted to said frame, and a recoilspring for opposing rearward recoil movement of the slide and for thenreturning the slide to its forward firing position, the improvementcomprising:

a recoil spring guide carried by said frame and encompassed by saidrecoil spring, said spring guide mounting a rearwardly projectingresilient bias element;

and a barrel link pivotally coupling said barrel link pin and said stoppin whereby said barrel and said slide are held interlocked in theirforward firing position and during their initial recoil, and said barrelis tilted out of interlocked relation with said slide during theirfurther rearward movement, said link including a camming surfaceengageable with said bias element for developing a progressively greaterupward bias upon said link during forward movement of said barrel towardits forward firing position, said bias being operative during saidinitial recoil to urge siirii rearward portion of said barrel againstsaid s 1 e.

2. The improvement in an automatic pistol as set forth in claim 1wherein said recoil spring guide includes a central bore and said |biaselement comprises an elongated leaf spring fixed within said bore andprojecting rearwardly therefrom.

3. The improvement in an automatic pistol as set forth in claim 1wherein said bias element comprises an elongated leaf spring having arearward portion rearwardly tapered in width for deflection in an archaving a more nearly common radius throughout the are.

4. The improvement in an automatic pistol as set forth in claim 1wherein said recoil spring guide mounts a transverse pin enga'geable bysaid bias element for limiting upward travel of said bias element.

5. In an automatic pistol having a frame with a recess, a recoilingbreech slide and a recoiling barrel mounted thereon for tilting at itsrearward portion relative to said slide and including a dependingportion mounting a transverse barrel link pin, means for interlockingsaid barrel and said slide, a transverse slide stop pin mounted to saidframe, and a recoil spring for opposing rearward recoil movement of theslide and for then returning the slide to its forward firing position,the improvement comprising:

a. recoil spring guide carried by said frame and encompassed by saidrecoil spring, said spring guide mounting a rearwardly projectingresilient bias element and including a rearwardly projecting lowerportion extending into the recess of said frame substantiallycoextensive with the projecting portion of said bias element to afford afirm seat for said spring guide on said frame;

and a barrel link extending into said recess and pivotally coupling saidbarrel link pin and said stop pin whereby said barrel and said slide areheld interlocked in their forward firing position and during theirinitial recoil, and said barrel is tilted out of interlocked relationwith said slide during their further rearward movement, said linkincluding a camming surface enaggeable with said bias element fordeveloping a progressively greater upward bias upon said link duringforward movement of said barrel toward its forward firing position, saidbias being operative during said initial recoil to urge said rearwardportion of said barrel against said slide.

6. In an automatic :pistol having a frame with a recess,

a recoiling breech slide and a recoiling barrel mounted thereon fortilting at its rearward portion relative to said slide and including adepending portion mounting a transverse barrel link pin, means forinterlocking said barrel and said slide, and :a transverse slide stoppin mounted to said frame, the improvement comprising:

a barrel link pivotally coupling said barrel link pin and said stop pinwhereby said barrel and said slide are held interlocked in their forwardfiring position and during their initial recoil, and said barrel istilted out of interlocked relation with said slide during their furtherrearward movement, said link including a lower camming surface;

and bias means mounted in the base of said recess and engageable withsaid camming surface for developing a progressively greater upward biasupon said link during forward movement of said barrel toward its forwardfiring position, said bias being operative during said initial recoil tourge said rearward portion of said barrel against said slide.

7. The improvement in an automatic pistol as set forth in claim 6wherein said bias means comprises a ball and a compression spring seatedin a bore provided in said frame, said ball being en-gageable by saidcamming surface of said link for developing said bias.

8. In an automatic pistol having a frame, a recoiling breech slide and arecoiling barrel mounted thereon, and barrel means depending from therearward portion of said barrel, the improvement comprising:

a transverse slide stop pin carried by said frame and positioned tocooperate with said depending barrel means for guiding the travel ofsaid barrel, said stop pin being radially resilient and engageable atits upper periphery with said depending barrel means for developing anupward bias on said depending barrel means in the firing positions ofsaid barrel to urge said rearward portion of said barrel upwardlyagainst said slide.

9. In an automatic pistol having a frame, a recoiling breech slide and arecoiling barrel mounted thereon for tilting at its rearward portionrelative to said slide and including a depending barrel lug mounting atransverse barrel link pin, means for interlocking sai-d barrel and saidslide, a barrel link carried by said barrel link pin for pivotalmovement relative to said barrel, and a recoil spring for opposingrearward recoil movement of the slide and for then returning the slideto its forward firing position, the improvement comprising:

a transverse slide stop pin carried by said frame and disposed throughan opening in said barrel link for pivotal movement relative theretowhereby said barrel and said slide are held interlocked in their forwardfiring position and during their initial recoil, and said barrel istilted out of interlocked relation with said slide during their furtherrearward movement, said stop pin being radially resilient and engageablewith said barrel lug for stopping said slide and barrel in said forwardfiring position and for developing an upward bias on said barrel link inthe firing position of said barrel to urge said rearward portion of saidbarrel against said slide.

10. The improvement in an automatic pistol as set out in claim 9 whereinsaid stop pin is split along substantially its entire length and bowedoutwardly for developing a bias upon being radially compressed againstsaid barrel link.

References Cited by the Examiner UNITED STATES PATENTS 8/1937 Williams89-l96 X 5/1956 Allen 89196-

1. IN AN AUTOMATIC PISTOL HAVING A FRAME, A RECOILING BREECH SLIDE AND ARECOLING BARREL MOUNTED THEREON FOR TILTING AT ITS REARWARD PORTIONRELATIVE TO SAID SLIDE AND INCLUDING A DEPENDING PORTION MOUNTING ATRANSVERSE BARREL LINK PIN, MEANS FOR INTERLOCKING SAID BARREL AND SAIDSLIDE, A TRANSVERSE SLIDE STOP PIN MOUNTED TO SAID FRAME, AND A RECOILSPRING FOR OPPOSING REARWARD RECOIL MOVEMENT OF THE SLIDE AND FOR THENRETURNING THE SLIDE TO ITS FORWARD FIRING POSITION, THE IMPROVEMENTCOMPRISING; A RECOIL SPRING GUIDE CARRIED BY SAID FRAME AND ENCOMPASSEDBY SAID RECOIL SPRING, SAID SPRING GUIDE MOUNTING A REARWARDLYPROJECTING RESILIENT BIAS ELEMENT; AND A BARREL LINK PIVOTALLY COUPLINGSAID BARREL LINK PIN AND SAID STOP PIN WHEREBY SAID BARREL AND SAIDSLIDE ARE HELD INTERLOCKED IN THEIR FORWARD FIRING POSITION AND DURINGTHEIR INITIAL RECOIL, AND SAID BARREL IS TILTED OUT OF INTERLOCKEDRELATION WITH SAID SLIDE DURING THEIR FURTHER REARWARD MOVEMENT, SAIDLINK INCLUDING A CAMMING SURFACE ENGAGEABLE WITH SAID BIAS ELEMENT FORDEVELOPING A PROGRESSIVELY GREATER UPWARD BIAS UPON SAID LINK DURINGFORWARD MOVEMENT OF SAID BARREL TOWARD ITS FORWARD FIRING POSITION, SAIDBIAS BEING OPERATIVE DURING SAID INITIAL RECOIL TO URGE SAID REARWARDPORTION OF SAID BARREL AGAINST SAID SLIDE.